The present invention, in some embodiments thereof, relates to methods and devices for sequestration and/or depletion of petroleum from water, and, more particularly, but not exclusively, to the use of electrospun microtubes for adsorption and/or sequestration of petroleum from the water, and optionally for further bioremediation of petroleum using the electrospun microtubes with bacteria encapsulated in or immobilized to.
Oil spills are caused by various triggering events and may reach hundreds of million gallons annually. These include for example, accidents and big spills (37 millions of gallons per year); routine maintenance which involves bilge cleaning and other ship operations (137 millions of gallons per year); used engine oil which ends up in waterways (363 millions of gallons per year); air pollution, mainly from cars and industry, which places hundreds of tons of hydrocarbons into the oceans each year (92 millions of gallons per year); off shore drilling (15 millions of gallons per year); and natural seeps (62 millions of gallons per year).
Crude oil and refined fuel spills from tanker ship accidents have damaged natural ecosystems in Alaska, the Gulf of Mexico, the Galapagos Islands, France and many other places. The quantity of oil spilled during accidents has ranged from a few hundred tons to several hundred of thousands tons. For example, the deepwater horizon oil spill in the Gulf of Mexico in 2006 on the BP-operated Macondo Prospect, which is considered the largest accidental marine oil spill in the history of the petroleum industry, involved a total discharge of oil estimated at 4.9 million barrels (210 million US gal; 780,000 m3).
Smaller oil spills have already proven to have a great impact on ecosystems because of the remoteness of the site or the difficulty of an emergency environmental response. For example, in 1989 the Exxon Valdez oil tanker struck Prince William Sound's Bligh Reef in Alaska and spilled 260,000 to 750,000 barrels (41,000 to 119,000 m3) of crude oil.
Oil spills at sea are generally much more damaging than those on land, since they can spread for hundreds of nautical miles in a thin oil slick which can cover beaches with a thin coating of oil. This can kill sea birds, mammals, shellfish and other organisms it coats.
The increasing number of marine oil spills calls for new and effective solutions for the environment.
To date, several approaches have been used to treat oil spills. These include, for example, the use of sponges made of pure carbon nanotubes, with a dash of boron atoms added, which can absorb oil up to 100 times of their weight (Daniel P. Hashim, et al., Covalently bonded three-dimensional carbon nanotube solids via boron induced nanojunctions. Scientific Reports 2, Article number: 363 doi:10.1038/srep00363, published 13 Apr. 2012); “metallic soaps”, iron-rich salts, which use a unique blend of gravity and surface tension, and which can be vacuumed off the surface after cleaning an oily patch; the Elastec Oleophilic Skimmers which employ a grooved plastic disc that rotates through the water and which can pull as much as 2,500 gallons of oil from water per minute; and the absorbent peat moss which can absorb up to 15 times its weight in hydrocarbons.
Bioremediation, i.e., a process by which chemical materials are degraded by microorganisms, has become a major mechanism for removing and treating oil spills and pollutants on affected shorelines, in open water, near-shore, coastal environments and inland. Among the different techniques to enhance natural biodegradation by indigenous microorganisms, seeding of new bacteria and fertilizing the indigenous populations have attracted most interest. The application of nutrients such as nitrogen and phosphorus in the form of fertilizers has shown to be most effective in accelerating the biodegradation process and at the same time to be environmentally safe.
WO2008/041183 publication discloses microtubes and methods of generating same.
WO2009/104174 publication discloses a method of attaching a cell-of-interest to a microtube.